Electrical heating element



Jan. 11,1927. 1,614Q33l E.. L. WIEGAND LBc'rRIcAL HEATING ELEMENT Original AFiled August 3l 192.7 2 yShee'asfShci. 1

1,614,331 JUL 11 v 1927 E. L. wlEGAND ELECTRICAL HEATING' ELEMENT Original Filed August `31, 1923 2 Sheets-Sheet .2

Patented 1l,k 1927. y

f UNITED STATES l 11,614,331 PATENT oFFlcE.

EDWIN' L. W'IEGAND,`OF BOROUGH, PENNSYLVANIA.

ELECTRICAL HEATING ELEMENT.

Uriglnal application'led August 81, 1923, Serial No. 660,294. i Divided and this application tiled December 24, 1924 Y My invention relates to improvementsin electrical heating elements, and more particularly to a novel type of electrical heatlng element that is especially suitable for use in connection with .various kinds of electrical appliances, the particular shape in which the element is ma e depending, in many 1nstances, upon the form or 4character of the appliance wherewith it is`to used.

his applicationis a divlsion of myapf. plication Serial No. 660,294, tiled August 31, 1923, and, with res ct to the generic' invention disclosed. in t is and my former case, the general ob'ects are to provide a durable,

' l'practically in estructible, simple and comparatively inexpensive yyet highly Aeicient electrical' heating element `com risinga resistor enveloped'in a, mass of re ractoryelectrical insulating heat conducting material that is'khilghly compacted or com ressed, as by vsuitab e power means, about t e reslstor and-within a sheet metal sheath or casing,

the element being relatively thin and, due to the thinness of the sheetv metal walls and a large ratio of surface area to mass, aiord- 4 ing maximum heat emis'svity.

Asbrought out in theorigmal application, the heating'element, by virtue of 1ts con struction and relatively thin walls and cross sec-tion, may bereadily shaped to lie in'intimate contact with'the object to be heated, thereby to minimize resistance to the transfer of heat from the element to the object.

invention 'wherein the element is in the nature .of a stri that is oblong in cross section and is thin relatively toits width, the l narrow edges of the element being other than straight in a linear direction. T erefore the disclosure, any shape between a slig t depar- .ture from a straight strip to a complete anlnulus, illustrative examples of the various shapes whichthe element may take being shown in the drawings accompanying and lfox-ming \a' part hereof and whereln 1 is 'a plan view of an annular heating element constructed in accordance with my invention; Fig. 2-is an edge view Ather-eo Fig. 3 is a plan view of an element of triangular lshape; Fig. 4de a similar .view of an open ring type element; Fig. 5 1s a plan view of .a heatin element having the shape of an inverted Fig. 6 shows, i-n plan, a heating element constructed in accordance with my lbinding `material`such as clay to This case is restricted to a `form of the element may assumegwithin the sco Ve of this Serial No. 757,798.

invention and designed for use in a sad iron base; Figs. 7, 8 and 9 show modifications of the invention in the nature of strips that are other than straight in a linear direction; Figs. 10 and 11 are transverse secti'onsmn the respective lines 10-10 and 11-11 of t-lie foregoing views; Fig. 12 is a further modificatlon of the invention, the element being of'annular form and having a web thatl extends across its central opening; 13 is an edge view of the element shown in Fig. 12; Fig. 14 is an enlarged sectional detail on the line 14-14 of Fig. 12; and Fig. 15 shows the form of the invention illustrated in- Fig. 1 dished for application to the curved bottom of a vessel that is indicatedin dotand-dash line.

In all forms of the invention, a sinuous resistor 1 is enveloped within a mass 2 of suit? able electrical .insulating heat conducting 7 material. The resistor referably consists of a flat ribbon Wire of. suitable metal shown as bent back and. forth across 4the element in comparatively close convolutions with its edges' presented to the broad faces of the element; and while I do not limit myself to any particular kind of refractory insulatin ma- -terial, one class found es ecially sultab e for 'the purpose 1s compose of ma or aluminum oxide, or zirconium silicate, either individually where possible or a compound of them, together,l when desirable, with a give the necessary plast1city during fabricatlon and to effect homogeneity in the final product.

The mass 2 of refractory material is high- 1 lycompacted, as by a suitable power press, Y within a sheet metal sheath or casing 'and about the resistor so that the resistor is'thoroughly surrounded and enveloped bythe material. In the forms of the invention illustrated in Figs. 1 to 9, the sheath* or casing is comprised of members 3 and 4 (see particularly Figs. l() and 11), the former being in the nature of a shallow sheet metal I casing having a relatively wide wall 5 from lthe opposite sides'of which `.extend at sub# stanti'ally right angles narrow marginal walls 6 which have their edges. flanged inwandly at 7 over the lateral edges or'mar- 105 structural details set forth.

The ends of the resistor 1 are connected to terminals l0 which have their enlarged inner ends or bases to which the resistor is attached embedded within the mass 2 of refractory material. The terminals extend outwardly through holes 12 of the cover 4, the holes being enough larger than the -terminals to insure proper spacing and consequential insulation from the casing and, as illustrated, the hole is closed by a Washer 13 of mica or Aother suitable insulating material that fits over the terminal and is engaged against the inner side of the cover 4.

n'the form of the invention illustrated in Figs. l2 to 14, the sheath or casing is comprised of the members 3:L and 4a which are substantially identical with the respective members 3 and 4'ofthe previously described casing and enclose the resistor 1 with the mass 2 of refractory material wherein the rc'- sistor is embedded. The casing member 3, in the present instance, is formed from the edge portion of a sheet metal blank, the part constituting the bottom wall 15 of the casing member 3EL being offset ,from the plane of the central portion or web 16 -and 'connected thereto by a wall 17 which, in the present form of the element, is cylindrical.' A peripheral wall 18 rises from the outer edge of the wall 15. Where the wall 17 joins the web 16, the material is crimped upon itself to Y form a iiange 19 that overlies the adjacent edge or mar inal portion of the cover 4a the same ast 'e free edge of the wall 18 is ianged inwardly at 20 over the outer edge or marginal ortion of the cover.

From the oregoing it Will be seen that the form of the invention illustrated in Figs.' 12 to 14 differs from that illustrated in Figs.

1 and 2 practically only by the inclusion ofl lthe web 16, and the center of this web is shown as having an aperture 21 through which a support' for the element may be extended. This construction is especially suited to certain installations, the web providing 'a very convenient means of attaching the element to an ap liance and serving also to close the space de ed by the element Where such is desired. -Aside from the supporting function of the web 16, it is particularly desirable in some classes of cooking appliances where it is preferred to close the central opening of the element to prevent food overflow or other substances from pa ss ing through the opening toy a substructure;

As previously stated herein, 4and as brought out in m original application above identified, the e ement may be formed to correspond to the contour of a vessel or other object to which the element is to be applied so that it will lie in intimate Contact with the object to be heated. In Fig. 15, an element designated 21, which may .be in the nature of that shown in Fig. 1 for example, is shown as dished to fit the curved bottom of -a vessel that is indicated at 22 by dot-anddash lines.

Having thus described my invention, what I claim is 1. As a new article of manufacture, an electrical heating element comprising a resistor, a sheet metal sheath enveloping said resistor and spaced therefrom, and a mass of granular refractory electrical insulating material filling the space between the resistor and the sheath, the element being oblong in cross section and thin relatively toits width, the narrow edges of the element bei-ng other than straight in a linear direction.

2. As a new article of manufacture, an electrical heating element comprising a res1stor, a sheet metal sheath enveloping said resistor and spaced therefrom, and a mass of granular refractory electrical insulating material iillin the spacebetween` the resistor and the sheat the elementl being in the nature of'a strip having edges that are spaced aparta substantially like distance throughout the length of the element and having an oblong cross section and' bein thin relatively to its width, the narrow ges of the element being other than straight in a linear direction. Y

3. As a new article of lmanufacture, an electrical heating element comprising a sinn'- ous ribbon resistor, a sheet metal sheath enveloping said resistor' and spaced therefrom. and a mass of granular refractory electrical insulating material filling the space between the` resistor and the sheath, the element being in the nature of a strip having edges, that are spaced a substantially like' distance apart throughout the llength of the element and having` an oblong cross -section and being thin relatively to its width, the edges of the sinuous ribbon resistor \bein lpresented toward the wider faces of the e ement, the nar- -row edges of the element being other than straight in a linear direction.

4. As a new article of manufacture, an electricalI heating element comprising a resistor, a sheet metal sheath enveloping said resistor and spaced therefrom, and a mass vof granular refractory electrical;insulating material filling the space between the resistor and the sheath, the element being oblong in cross section and thin relatively to its'wldth and having the form of an annulus.

5. .As a new article ofr manufacture, an electrical heating element` comprising a. resistor, a sheet metal sheath enveloping said resistor and spaced therefrom, and a mass of granular refractory electrical insulating material 'filling the space between the resistor andthe sheath, the element be' inthe nature of an endless strip that is thm relatively tp it's wlthL the inrller nsrow edge of the e ement emng' a ativ opening.

6. As anew article of gimme, an electrical heating element comprising a re;

lll() x in sistor, a sheet metal sheath enveloping said resistor and spaced therefrom, and a mass of granular refractory electrical insulatingl I its width, the narrow edges of the element material filling the space between the being other than straight in -a linear direction, the said sheath being constructed of two main sections having their margins disposed adjacent the narrow edges of the mass of insulating material and connected together.

'TLAs a newr article of manufacture, an

electrical heating elementcomprising a resistor, asheet metal sheath enveloping said resistor and spaced therefrom, and a mass granularrefractory electrical insulating material filling the space between' the re- -sistor and the sheath, the element being oblong in cross section and thin relatively to its width, the narrow edges of the element being other than straight in a linear direction,

the said sheath being'y constructed of two sec-v tions, rone having marginal flanges whichl extend over the narrow edges of the mass of insulating material and are connected to thev marginof the other section.

8. Asa new article of manufacture, an electrical heating element comprising a resistor, a sheet metal sheath envelo ing said resistor and spacedJ therefrom, and a mass of granular refractory electrical insulating resistor and the sheath, the element beingy oblon in cross section and thin relatively to its wi th, the narrow edges of the element being other than straight in a linear direction, the said sheath being constructed of two sections, one 4o, 1

the narrow edges of the mass of insulating iaving marginal flanges whicliextend over material and are turned over the marginal portions of the other section.

9. An electric resistance heating element P comprising an annular hollow sheet metal body having a flat working face, a sinuous resistorelement of flat ribbon wire located inside said bod;7 extending generally circumferentiall thereof but sinuousl back and forth wit 1in said body and space therefrom, the edge of the wire being presented toward said working face, and a mass of granular refractory electrical insulating material fillin the space between the resistor and the bo y.

10. An electrical heating element comprising a sheet metal member havin its edge portion offset from the plane of its central port-ion by a relatively narrow wall, the member having a peripheral wall opposed to said narrow wall thereby to form a shal-I low channel shaped casing,-a mass of granular refractory electrical insulating material filling said channel, a resistor embedded within said mass of insulating iiiatei'ial and about which the material is compacted, and l a cover closing the open side the edges Lof said Cover and narrow walls being l1. Anelectrical of the casing,

connected together.

heating element comprising a circular sheet metal member having its edge portion offset from the plane of its central portion by a relatively narrow substantially'cylindrical wall, the member having a peripheral wall concentric with Said narrow wall thereby to form an annular shallow channel shaped casing, a mass of granular refractory electrical insulating material filling said casi-ng, a resistor embedded within said mass of insulating material-and about which said material is compacted, and an annular cover closing the open side of the casing, the edges of the aforesaid walls being turned over the edges ofthe cover.

signature.

EDWIN L. 'wiEGANng the aforesaid A 

